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  1. ramussons

    Power supply help

    :)
  2. ramussons

    Keypad with 3 pin hall effect sensor

    Is that a Keyboard Matrix Decoder on the Top Right? My Understanding is that the "ROW" voltage is reduced and the "COLOUMN" voltage is increased when a Key is Pressed (or the other way ). I don't think the "Diode" setup will work.
  3. ramussons

    Keypad with 3 pin hall effect sensor

    Yes Yes. The Hall Sensor cannot drive the Opto's. You will need to interface a CMOS Buffer to drive the OPTO's. Can we have a schematic of what you propose?
  4. ramussons

    Power supply help

    By pass the Temperature Sensor and see what happens.
  5. ramussons

    Stk412-150 Sony Amplifier

    From the schematics, it seems that no alteration needs to be done in the Power Amp Board. Connector B is the Signal Input with a MUTE control (Gnd for MUTE, 5.0 V (?) for Un MUTE). Connector C is the Speaker Out. Connector L is the Power Supply - There are 2 AC voltage inputs. You will need...
  6. ramussons

    UPS - mains voltage / output voltage not synchronized

    If yours is an "Online" UPS, its output voltage and frequency is not dependent on the Input. It will have it's own Frequency and Output Voltage, both which can be set. But, as mentioned in the earlier post, the make and Model Number will be helpful in getting better information.
  7. ramussons

    Stk412-150 Sony Amplifier

    Do you have the schematic of the Sony system?
  8. ramussons

    Keypad with 3 pin hall effect sensor

    You can try using an Opto Coupler to replace the mechanical switches in the 3x4 array. The Opto could be triggered by the Hall Sensor output.
  9. ramussons

    Power supply help

    When the supply shuts down, can you feel the heat sink for any high temperature? (be careful). The temperature sensor could also be the culprit.
  10. ramussons

    Power supply help

    Over Temperature is a possibility. Is there a working cooling fan? Dust on the Heat Sinks?
  11. ramussons

    Laptop cooling pad circuit board.

    First, let's confirm its a pot or a switch. Did the original have 2 speeds or a variable speed? My guess is it had variable speed, in which case, it's a pot. Can we have a good photos of the 2 sides of the board?
  12. ramussons

    Laptop cooling pad circuit board.

    Looks like a potentiometer with a switch, like the ones used in pocket radios. Normally 10 K ohms. Try Mouser.... http://www.mouser.in/ProductDetail/Alpha-Taiwan/RV121SF-30-009J-A10K-00K/?qs=sGAEpiMZZMtC25l1F4XBU8QYBPm8%2b83CBUoFz2pDjOU= Or Alibaba
  13. ramussons

    Ceiling fan speed transformer

    Its a simple Choke with tappings in series with the fan to control speed. Had that on one of fans during the 60's.
  14. ramussons

    SCR series regulator

    If you need about 48 VDC @ 7A from 110 VAC, the best is to use a SMPS as Bluejets suggested. If you still want to use a SCR type regulated supply, you need to, first of all, get a 110 V - 48 V transformer rated at about 500 VA. Communication equipment used these type of Power Plants during the...
  15. ramussons

    Induction Stove

    You mean a DC input? https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiG8uONztDUAhXFPo8KHbBBBcUQFgglMAA&url=http%3A%2F%2Fwww.st.com%2Fresource%2Fen%2Fapplication_note%2Fcd00115561.pdf&usg=AFQjCNGm10gsj5mpwGCVF48aGlTCxT1FOA
  16. ramussons

    Calculate Op Amp Gain

    A = [1 + ( (R1 + R2) / R3)] * (R2+R3)/(R1+R2+R3)
  17. ramussons

    Equivalent for a some ICs from the '80s

    Does this help? https://www.digchip.com/datasheets/parts/datasheet/235/CA3189-pdf.php
  18. ramussons

    Can SAMSUNG laser printer toner errors be over-ridden? (Scan ONLY).

    Scanning should be possible even when the print cartridges are empty. Normally, a SCAN button on the Printer will, by default, print a copy, in which case, print cartridges are required. If you are trying a SCAN from the computer, it should work. Unless Samsung is playing dirty :(
  19. ramussons

    Changing Ceiling Fan Capacitor

    For even a 230 V AC fan, 400 V AC capacitor is good enough.
  20. ramussons

    Alternative switch

    http://www.ti.com/lit/ds/symlink/sn74hc151-q1.pdf
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